1. Field of the Invention
The invention relates to compositions comprising a hydrogel matrix, where the matrix comprises poly(ethylene glycol) dimethyacrylate (PEGDMA), an acrylate, such as methacrylic acid (MAA) and methyl methacrylate (MMA), as well as 2-hydroxy-2 methyl propiophenone (HMPP).
2. Background of the Invention
A rapidly advancing area of biosensor development is the use of periplasmic binding proteins (PBPs), to accurately determine analyte, e.g., glucose, concentrations in biological samples. In particular, glucose-galactose binding proteins (GGBPs) are being employed as biosensors to measure analyte quantities in industrial and pharmacological physiological settings. PBPs are considered to be “reagentless” and can be used in a variety of settings including measuring glucose in monitoring diabetes, measuring amino acids in other metabolic diseases, such as histidase deficiency, as well as measuring arabinose during ethanol production from corn. Wild-type GGBPs, however, may not be the most ideal candidates for measuring or determining analyte concentrations for a variety of reasons. Biosensors comprising (GGBPs would preferably be physically stable under conditions of use to generate a quantifiable signal on glucose binding. When the intended use is to monitor in vivo glucose concentrations in diabetics, the proteins would preferably be stable at physiological temperatures. Additionally, the GGBPs would preferably have enhanced stability throughout sensor manufacturing, shipping and storage, which could enable the protein and sensor materials to be fabricated at ambient temperature. This manufacturing process could include high-temperature sterilization procedures for use in a clinical setting. Exposure to high temperatures, however, may denature the protein, rendering the GGBPs useless for their intended purpose.
A implantable biosensor could be used to constantly monitor the physiological state of a subject with a medical condition such as diabetes. The ideal biosensor for monitoring the levels of a ligand or target analyte would need to be biocompatible so that the biosensor would not provoke an immune response or be subject to bio-fouling. To develop biosensors using analyte binding molecules, especially binding proteins, the binding molecules must be physically or chemically immobilized within a biosensor hydrogel in a manner that allows analyte-induced conformational change of the binding molecules. In addition, methods of chemical attachment are needed that prevent loss of the binding molecule, and provide a stable, continuous and reversible biosensor response to changing concentrations of the analyte of interest. The hydrogel matrix must be permeable to the analyte, prevent interference from other biomolecules, and be biocompatible and biostable.
Previously, binding proteins have been successfully conjugated to several natural and synthetic polymer hydrogels like alginate, crosslinked multi-arm PEG-NH2 and poly(2-hydroxyethyl methacrylate) (PHEMA) and demonstrated reversible glucose binding. There are various performance deficits that hinder these materials from moving into product development. These deficits include decreased control over the rate of polymerization and swelling, poor mechanical stability, increased bioreactivity, etc.
PEG is a well-known biocompatible, nontoxic, non-immunogenic, water-soluble polymer widely used in biomaterials, biotechnology, and medicine. PEG can be modified with different functional groups useful for crosslinking with other monomers or conjugating biomolecules. There are various methods of crosslinking PEG and its derivatives into hydrogels for use in biosensor applications. Inappropriate crosslinking of PEG or PEG based derivatives, however, may produce hydrogel polymers possessing less than desirable properties for use as a biosensor.